JPS63116991A - Method and device for determining position of underwater body to towing ship - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a method and apparatus for determining the position of an underwater object relative to a towing vessel.

The invention particularly relates to a method and apparatus for determining the position of elements of a seismic wave transceiver device towed underwater by a ship, with respect to a number of locations whose positions relative to the ship have been determined.

Acoustic telemetry methods for determining the position of an object or hull towed underwater by a vessel are known, in which the transponder is submerged at a predetermined point in a predicted travel zone and the distance between the towing vessel, the transponder and the vessel is determined by acoustic telemetry. be. The position of the towed object or hull relative to the ship is calculated by triangulation. Such a method is described in patent US-4.2
29,809.

The accuracy obtained is good because the spacing between the transponders is of the same size as the distance to be measured.

However, it is difficult to use this method because it is necessary to place a marker indicating the progress zone in advance by submerging the transponder in water.

This is particularly inconvenient when the markings have to be specially installed for a particular application, or when the marking area is extremely large, such as in marine seismic exploration.

Other methods are also known in which the underwater position of a towed object can be determined, but in this case a seismic tube (flut
Regarding the position of each point of e sfsmlque), refer to patent U
There is a description in S-4,378,3 old.

In this method, the distance between two acoustic shock sources fixed on a ship is determined by acoustic telemetry, the source location being precisely known, and each hydrophone placed along the tube.

The specification of French Patent No. 2,545,228 also describes a method for determining the underwater position of a seismic tube towed underwater, but this basically involves determining the distance from a ship to multiple points along the tube and the distance between each point. Orientation is measured using a gyro compass and an extremely short-based fluidic sound system.

For very practical reasons, the spacing between the reference points at which the sonic transducer of an acoustic telemetry system is fixed relative to the ship is often very small relative to the length of the towed object, which means that multiple transmission It is a problem with the equipment or seismic tube.

The distance between reference points ranges from tens of centimeters to several meters, whereas seismic tubes span many kilometers.The triangle formed by the base reference point and each point of the seismic tube is unbalanced, so this This has a significant impact on the accuracy of telemetry or triangulation performed from

A method for determining the position of an underwater towed object relative to a towing vessel is known from French patent 2,533,708.

An auxiliary vessel is located parallel to and behind the towing vessel.

The relative positions of the two ships are determined by triangulation using conventional radio navigation systems and hydrosonic transponders.

The position of the towed object (in this case the seismic tube) is determined by triangulation using an acoustic telemetry system consisting of a ship's transceiver, a sonic receiver on the auxiliary ship, and a sonic transponder placed along the towed object.

The use of this method therefore requires two automated ships, each equipped with a radio navigation positioning system and a radio transmission system that transmits to the main ship a signal indicating when the sonic response reaches the auxiliary ship. Furthermore, although the sonic transmitter and receiver connected to the vessel are located in relatively shallow water, the surface water, especially in the wake, is choppy, making detection of the sonic signal difficult.

A detection system for determining the underwater position of a seismic tube relative to a towing vessel is also known from patent WO 84103153. The system comprises a sonic transponder fixed to a towed rose vane offset laterally to the ship's arch. The position of the seismic tube is determined in this case by acoustic telemetry for transponders.

In the method according to the invention, a sound wave receiving means is provided for a detection system connected to a ship with a mobile detection station having at least one acoustic transceiver system which is towed underwater and displaced laterally with respect to the ship's trajectory. It is possible to determine the position of an underwater object coupled to a ship and towed underwater by a ship by measuring the propagation time of the sound waves on the path between the detection system and said object, which method involves the various methods described above. There are no shortcomings.

A single vessel, suitable towing and transverse deflection means constitute a long detection base, and the underwater position of the towed object can be determined by sonic telemetry.

The measurement accuracy obtained is particularly good due to the large lateral separation separating the towed transmitting and receiving systems.

The use of relatively deeply submersible deflection means allows for separation from disturbances that affect the propagation of the acoustic signal due to water motion and vortices in the ship's wake.

Furthermore, the position of the towed sonic transceiver system constituting the mobile detection station is regularly determined relative to the detection station fixed on the ship, taking into account possible variations in the towing conditions. The measuring means immediately incorporates the telemetry results of two stages, one measuring position of the towed system relative to the ship and the other measuring position of the object relative to the same system, both stages being carried out alternately.

The characteristics of this method are as follows: the detection system further comprises a detection station fixed on the ship and having at least two sound wave transmitting/receiving systems; a first cycle of acoustic telemetry of the position of the towed object, at least one second cycle of acoustic telemetry of the position of the receiving means coupled to the towed object relative to the mobile detection station; decide. Further advantages of the method and features of the device for its use will become apparent from the description of the embodiments, which are given as non-limiting examples.

The method according to the invention comprises, for example, a seismic tube 2 towed at the tip of a traction cable 3 and one or more acoustic shock sources 5 (S
+, Ss-Ss-S4, etc.) with respect to the ship 1 (FIGS. 1 and 2) can be determined.

The sound source 5 is connected to the ship by a multifunction or "belly" cable 6. These cables, or parts of them, are fixed to another cable 7 which connects the ship with a deflection device 8 which is laterally displaced from the main line when being towed.

Mention may be made of rose vanes, panels or platforms as described in French Patent No. 2,29G, 5[i2. Generally, two deflection devices are used which are suitable to be offset symmetrically with respect to the ship's trajectory.

The method according to the invention submerges two acoustic transceiver systems ER1, ER, in fixed positions relative to the ship. The system comprises transmitting and receiving transducers each housed inside a long submersible rod 9 that assumes a vertical position relative to the hull in operation.

Also used is the rod described in French patent EN 8G 109,321. Each transducer is connected to a transmitting/receiving device (FIG. 2), which will be described later, by a line passing on the ship along the rod 9.

Both deflection devices 8 each have two acoustic wave transmitting/receiving systems E.
Install R3 and ER. For example, automatic transmitter/receivers of the "transponder" type can also be used, which are capable of retransmitting a signal at a characteristic frequency when receiving a sound wave signal.

Also, if possible, use a sonic transducer connected to a transmitter/receiver. This transceiver is powered and connected to the control device 10 by a multiconductor cable attached to a corresponding towing cable 7 (not shown).

Deflection devices and especially those related to position determination with respect to ships, such as power sources 5r-8s, are equipped with sonic receivers. A transducer may also be used which is optionally coupled to a receiver circuit and which emits sound waves in response to received acoustic signals or a transducer which is coupled by a transmission line to a control device. Either case can be adopted for marine earthquake sources.

When using transmission/feed lines, each power source is included in a multifunctional coupling system θ that connects to the ship.

If this method is used to determine the location of the seismic tube, transponders mounted on the outside of the tube at a point or several distant points can be used.

It is also possible to incorporate the transducers CF+-CFa-CFJ-CF1 into one seismic tube, but the transducers can also be connected by one or more special wires or by different combinations of multiple seismic tubes as described in French patent 2.511,772. It is linked to the ship's recording equipment via a seismic collector inserted between the sections.

The method according to the invention includes a first sonic telemetry cycle for the determination of a mobile station constituted by a system ER,,ER4, at a frequency f, by a first transceiver system ER, fixed to the ship which is controlled in sequence as follows: Transmission of the acoustic shock, which after underwater propagation is carried out by a second system ER2 installed on the ship and a transposed transmitting and receiving system E Ra of the towed mobile station.

Received by ER.

Also, the frequency f due to the other system ER,! transmission of acoustic shocks at the first system ER, and the transposed systems ER,,ER of the towed station.

received by.

Next, the telemetry results of both series are combined, and the distance between the first transmitting and receiving systems ER and ER is determined as 1. and L□, and the distances LII'5L23·, L, 4 and L24 separating both first systems from the transposed systems ER and ER,
(Figure 3).

According to this first result, the refixation system ER.

ER, and determine the coordinates of the towed station (ERs=ER4) connected to the deflection means.

A second sonic telemetry cycle is then obtained for positioning the towed object relative to the mobile station (ERas ER4). Therefore, when the transponder is connected to an object, the following controls are performed in sequence. Frequency f due to ERs
0 (Fig. 4), in the transponder TR, which is coupled to the towed object SI (the number 1 in the case shown in the figure).
is equal to 1°2.3 or 4) and is also received by the special receiver CF of the seismic tube (again, the number is equal to 1 or 2, for example). Upon receiving a pulse, each transponder retransmits at its natural frequency FR, (TR,', TR
,', TR3', and TR4 are the frequencies F R'+, respectively.
in response to F R2′-F Rs′-F Ra).

The retransmission signal is transmitted by four transmitting/receiving systems ER.

E Rs = E Ra, captured at E Ra and transmitted to the central system 10 on board the ship. Similarly, the signals captured by the seismic tube's dedicated receiver CF, are sent to the same central system by transmission lines inside the seismic tube.

For each transponder TR, the propagation distance (di, +
+ (11, s), (d s + + + d + , t
), (ds, ++d+, 2) and (d4.++d+
, a) can be determined (Figure 4). The dedicated receiver CF likewise has a distance d81. can be applied.

While repeating the same operation from ER and applying the following values to each transponder R1 and each receiver CF of the seismic tube (
d4t++d+ta), (d4.++dshil) 1(d
a*1+dl+1) N(d3,++d+,a) and on the other hand d4-,+CC10° Knowing the distance between the transmitting/receiving system and the various objects towed, its coordinates with respect to the ship can be determined respectively.

The device to be used firstly sets the frequency fo of the sequencer 14 to
Three signal oscillators generating signals at fs-f* 11.1
2.13 and 4 games) ET15.18117.1
8, which sequentially generates various transmission signals (FIG. 5). Sequencer 14 is clock element 1B
A program counter connected to the Game H5-18
Four time-displaced pulses are sent from the sequencer to four outputs S, , S, and S4 connected to the control input of the sequencer.

The gates 15 and 16 transmit the frequency f to the transducers T and T of the transmitter/receiver system ER and ER2 via a power amplifier 20, respectively.

and controls the pulse supply of f2. Similarly gate 1
7 and 18 are respectively connected to the transducer T of the transmitting and receiving system ER, ER, of the towed station via an amplification stage 20.
3. Control the sequential application of frequency f0 pulses to Ta.

The device also includes a receiving and telemetry system. The acoustic signal received by the transducer Ts=Ta of the transmission/reception system of the towed station (ER3, ER,) is sent to the preamplifier 2.
1 and then telemetry system E3. Ea (FIG. 6).

In order to separate the signals of the fixed transceiver system ER, ER and the separate system ER of the mobile detection station (ER
, and vice versa), it is equipped with three narrowband filters 220, 221 and 222. Furthermore, the number of narrowband filters (
In the illustrated example, there are four filters 231.232.233.2
34) (Fig. 7).

These filters are connected to each transponder TR+-T
Frequency FRI'-FR2 output from Ra-TR5-TR4
The signals '-FR3'-FRJ' can be separated. The signals from the filters are each passed through a counter 240.241.2.
42, and the other is the counting system 240 counter 251~
254. These counters connected to electrical element (H) 19 measure the propagation time of signals sent at various frequencies. The counts of systems E and 9Ea (FIG. 6) are input to both input sides Bs and B4 of the storage device 2B, respectively.

The acoustic signals captured by the seismic tube transducers CF, CF1, CF, are sent to the preamplifier 2I and then to the element 2.
7. , 27. , 27. and displaces its frequency by the characteristic amount of each transducer.

Element 27. is the frequency displacement df, element 27. is the displacement d
Do f. Total displacement element 27. , 27. , 27.
The output side of is connected to a common line 28 that runs along the seismic tube and is further connected to a receiving and telemetry system on board the ship.

Line 28 is the transducer CFI- placed in the seismic tube.
CF2-CFJ-CF, and are coupled to the same number of telemetry systems EF1, EFJ, EFI.

Each system EFIj EFJ-EF comprises a narrowband filter corresponding to systems E3 and B4 (Fig. 8) (
291.292.293 and 301-30 for 7
4). However, the center frequencies are each displaced by the same amount to separate the signal displacement from the corresponding transducer from the others. For example, the displacements df1, df, dfl correspond to the transducers CF, CF, CF. ), and similarly separates acoustic signals output from various transceivers ER1 to ER4 and various transponders TR. Similarly, the signal from the filter is sent to a counting system 24.

The measured values by the counters of the systems EF,...EF,...EFn are input to the input sides BF1 and BF of the storage device 2B, respectively.
,, sent to BFn. (FIG. 6) A storage device is connected to a computer 31 in which the position of the transceiver system ER,, ER, of the mobile station relative to the ship is determined according to the various values stored during the acoustic telemetry with both cycles.
Determine the position of the towed object relative to the mobile station and therefore the position of the object relative to the ship. The calculation results are displayed on the display 32.

The receiving and telemetry system also connects via a preamplifier 21 to the transducers T, n of the fixed detection stations ER,, ER,
It also comprises two telemetry systems Els E2t each coupled to t T, respectively. The systems E and B2 are similar to the systems E3 and B4 described above, and the values measured by the respective counting systems are entered into two inputs B and B2 of the storage device 26.

[Brief explanation of the drawing]

FIG. 1 shows a ship towing a transmitting device and a seismic tube behind it and equipped with a sound wave transmitting and receiving system. FIG. 2 shows, in a top view, the ship with acoustic transceiver systems arranged symmetrically on either side of the ship's orbit and forming two detection stations. Figure 3 shows the various trajectories measured between the transmitting and receiving systems of ship-based and mobile station □. Figure 4 shows the various distances measured between the towed object and the transmitting/receiving systems of both detection stations. FIG. 6 shows a schematic diagram of the control system for generating the transmitted acoustic pulses. FIG. 6 shows a schematic diagram of a receiving and telemetry system for determining the relative position of various towed objects with respect to fixed and mobile stations. FIG. 7 shows a schematic diagram of the telemetry system connected to each acoustic wave transmitting/receiving system. Figure 8 shows a schematic diagram of the telemetry system coupled to the various receivers of the seismic tube. 1... Ship 2... Earthquake tube 3...
... Traction cable 4 ... Transmission device
5... Acoustic pulse source 8... Deflection device 9... Rod ER... Fixed transceiver system TR... Transponder FR...
...Frequency If, 12.13...Signal oscillator 1
5-18...Gate 20...Amplifier T
...Transducer 220-222...Filter EF...Telemetry system CF...Transducer 24...Counting system 26. ·····Storage device

Claims (10)

[Claims] (1) In connection with a detection system connected to a vessel, towed underwater by a vessel equipped with a mobile detection station having at least one acoustic transceiver system (ER_3, ER_4) displaced laterally with respect to the trajectory of the vessel. and the position of the underwater object connected to the sound wave receiving means is determined by the detection system and the measurement of the propagation time of the sound wave in the path between the objects, the detection system further being fixed to the ship and having at least two
It is equipped with a detection station with two sound wave transmitting and receiving systems (ER_1, ER_2), and a detection station (ER_2) fixed on the ship.
1, ER_2) in relation to the mobile detection station (ER_3, ER
_4) a first cycle of teleacoustic measurement of the position of the mobile detection station; and receiving means (
At least one second remote acoustic measuring device (TR, CF)
A method characterized in that it implements a cycle and also determines the position of an object towed with respect to a ship. (2) a sonic receiver connected to said objects (2, 5), at least one sonic transceiver system (E
R_3, ER_4), a ship-fixed detection station consisting of mutually separated acoustic wave transmitting/receiving systems (ER_1, ER_2), outputting pulse signals (f_1, f_2) of two different frequencies; A control system connected to the transmitting/receiving system for sending to the transmitting/receiving system of the fixed detection station and outputting a pulse signal of the third frequency (f_0) to send to each transmitting/receiving system of the mobile detecting station, and a system of the detecting station fixed on the ship. comprising a receiving and telemetry system coupled to the transmitting/receiving system and each acoustic receiver for determining the position of each transmitting/receiving system of the mobile locating station relative to the transmitting/receiving system of the mobile locating station and the position of each receiver relative to the transmitting/receiving system of the mobile locating station. Claims (1)
). 3. The apparatus of claim 2, wherein each acoustic receiver is coupled to a transponder (TR) of a fixed retransmission frequency. (4) a submersible panel connected to the vessel by means of towing means to be towed away from each transmitting/receiving system, and supplying power to the coupled transmitting/receiving systems to connect said transmitting/receiving systems, control systems, and receiving/remote sensing systems; 2. Device according to claim 2, characterized in that it comprises at least one cable for transmitting signals to. (5) The control system is a detection station transmitting/receiving system (ER) whose output side is fixed to the ship via gates (15, 16).
_1, ER_2) respectively connected to different frequencies (
f_1, f_2) signal oscillators (11, 12) of a third frequency (f■) whose outputs are connected via another gate (17, 18) to the transceiver system (ER_3, ER_4) of the mobile detection station. characterized in that it comprises a signal oscillator (13) and programmable counting means (14) connected to the clock element (19) for outputting pulse signals and feeding them to the control inputs of the gates (15-18). Scope of patent claims (3
). (6) The receiving/telemetry system includes a plurality of telemetry systems (E_1 to EF_n) each having a plurality of filter means (22, 23) in order to separate signals received by the transmitting/receiving system according to frequency, and the above-mentioned signals. A patent claim characterized in that it also comprises counting elements (24, 25) for measuring the propagation time of the object, and calculation means (31) for determining the relative position of the towed object with respect to the transmitting and receiving systems (ER_1 to ER_4) of both detection stations. The device according to scope (3). (7) Each acoustic receiver fixed on each towed object (5) is connected to a transponder (TR) retransmitting at a specific frequency (FR_1 to FR_4), and each telemetry system is connected to a specific frequency of retransmission of the transponder. 6. Device according to claim 6, characterized in that it comprises filter means (22, 23) adapted to. (8) One of the towed objects has a different transmission/reception system (FR
at least one acoustic receiver (CF_J) connected by a transmission line (28) to a telemetry system (EF_J) having a plurality of filter means and counting means for measuring the propagation time of the signals transmitted from _1 to FR_4); The device according to claim 6 or 7, characterized in that it is an earthquake tube (2) comprising: (9) characterized in that the telemetry system (EF_J) connected to each acoustic receiver (CF_J) of said tube (2) is provided with filter means (29, 30) adapted to separate the acoustic signals emanating from different transponders; The device according to claim (8). (10) The seismic tube is equipped with a plurality of acoustic receivers (CF_1 to CF_n) connected in parallel on a transmission line (28), and each acoustic receiver calculates the frequency of the signal it receives using a feature value (df_
1 to df_n) (27_1 to 27_
n), and the receiving and telemetry system comprises a plurality of telemetry systems (EF_1 to EF_n) each connected to a respective different acoustic receiver (CF_1 to CF_n) of the seismic tube, each system (CF_1 to CF_n) is a different transmitting/receiving system (ER_
1 to ER_4) and a transponder (TR_J) connected to the towed object.